The present invention relates generally to mail and/or package handling systems. More specifically, the present invention relates to mail and/or package handling systems for environments where biological hazards may be present. Corresponding methods and protocols for mitigating the biological hazard are also disclosed.
Many organizations, e.g., various branches and departments of government and family planning clinics, have long operated under the threat of receiving one of several biologically hazardous materials. Since September 2001, the entire country has become aware of biologically hazardous material being delivered via the U.S. Postal Service. The entire world now knows that anthrax spores can be delivered in this manner. Other, commercial shipping services may also become the delivery mechanism for biologically hazardous materials.
Systems exist for destroying biologically hazardous material. For example, microwave and gamma radiation sterilization systems are available from various sources. However, such equipment is prohibitively expensive for facilities handling a few hundred letters/packages per day. Until regional sterilization facilities can be built, personnel may encounter biological hazards in delivered mail and packages. Since the most serious risk to personnel in the most often encountered biological hazards is through inhalation, what is needed is an apparatus, which permits personnel to perform routine mail handling tasks while minimizing the risk of inhaling or ingesting biologically hazardous material.
One potential mechanism for preventing the spread of biological hazard escaping from received letters/packages is to employ a vacuum device, e.g., a shop vac, in the central mail handling area. This proposed solution creates the following problems:
1. The spores associated with biological hazards such as anthrax are small. One of the periods appearing on this page could accommodate thousands of such spores. The air handling systems for most conventional vacuum systems are not sized to capture such spores; the spores are exhausted from the vacuum system. Thus, the exhaust of the conventional vacuum system promotes, rather than suppresses, airborne spores.
2. Vacuums equipped with high efficiency filters such as HEPA filters and Ultra filters are generally capable of removing airborne spores. However, HEPA equipped vacuums locate the HEPA filters downstream of the blower in the vacuum system. In that case, while the HEPA will prevent or at least minimize the exhausting of particulate biologically hazardous material, it does so at the expense of contaminating all upstream components in the vacuum system.
3. Vacuum systems, with or without HEPA filters, are generally noisy. While ear protection devices can be employed, such devices generally interfere with the other duties that mail-handling personnel are often asked to perform.
Many systems of implementing the vacuum system concept discussed in general terms above are known. For example, U.S. Pat. Nos. 5,807,414 and 6,290,740, both of Schaefer, disclose worktables for the performance of welding and grinding procedures. Each of the apparatuses disclosed includes a large work surface formed from a plurality of panels, each panel having a high number of perforations, which permit a high flow rate at a relatively low noise level. A fan is pneumatically coupled to the rear of the workbench. The fan discharges to one of a discharge filter housing enclosing a pre-filter and a final filter or a dust collector. In contrast, U.S. Pat. No. 5,984,990 to McDonald discloses a worktable for machining operations producing fiber particles or residue. Air flows through a number of grates, each equipped with a damper for controlling airflow, and is collected in a plenum discharging to a filter stack. A fan is disposed downstream of the filter stack to provide a negative pressure at the outlet of the filter stack; the fan discharges to the workspace where the work table is located.
In addition, there are myriad ways to sample a potentially hazardous area stream, such as those generated by the vacuum systems mentioned immediately above. For example, U.S. Pat. No. 4,754,655 to Parker, III et al. discloses an apparatus and method for sampling hazardous material. The apparatus comprises a conical shroud (plenum); a sampling nozzle; a filter; extension tube; a vacuum hose and a vacuum device. The sampling nozzle that is operatively coupled to the vacuum device forextracting a sample of the material from goods suspected of being hazardous. An optional HEPA filter is disposed downstream of and separate from the sampling nozzle.
There are also several mechanisms by which potentially hazardous materials can be sampled for identification. For example, U.S. Pat. Nos. 5,854,431 and 6,085,601, both to Linker et al., disclose a particle pre-concentrator apparatus which permits detection of highly diluted amounts of airborne targeted substances, such as explosives, narcotics or chemical agents. The apparatus comprises a filter for filtering particles in a main gas stream, such as a stream of ambient air and carry them to a particle detector, such as an ion mobility spectrometer. The apparatus further comprises a fan for inducing the movement in the air stream.
Based on the above and foregoing, it can be appreciated that there presently exists a need in the art for a biological hazard mitigation apparatus which overcomes the above-described deficiencies. The present invention was motivated by a desire to overcome the drawbacks and shortcomings of the presently available technology, and thereby fulfill this need in the art.
In one aspect, the present invention provides a biological hazard mitigation apparatus permitting a material handling operation in the vicinity of a work area, including a plenum pneumatically coupled and proximate to one side of the work area, a filter sized to trap biological hazards and including an exhaust port, a blower including an inlet port and an exhaust port, and ducting pneumatically coupling the exhaust port of the filter to the inlet port of the blower, wherein the filter is disposed in the plenum, and adjacent surfaces of the filter and the plenum are substantially equal in surface area. If desired, the ducting includes first and second ducts, permitting a silencer to be disposed between the first and second ducts. In an exemplary case, the filter includes a polishing filter disposed downstream of a roughing filter. The roughing filter can be a bag filter while the polishing filter can be a pleated paper filter. Alternatively, the filter can be a HEPA filter.
The biological hazard mitigation apparatus advantageously can include a plurality of legs, and a work surface supported by the legs, the work surface including an upper surface and a lower surface. If desired, the work area includes a portion of the work surface having air passages therein to permit airflow between the upper surface and the lower surface, and the plenum is operatively coupled to the lower surface of the work surface adjacent to the work area. In an exemplary case, the filter is accessed via the work area. In another exemplary case, the filter and the blower are disposed on opposite sides of a wall. The wall may be the exterior wall of a building and, thus, the exhaust port of the blower discharges to the environment.
In another aspect, the present invention provides a method for operating a biological hazard mitigation apparatus permitting a material handling operation in the vicinity of a work area, the apparatus including a plenum pneumatically coupled and proximate to one side of the work area, a filter sized to trap biological hazards and including an exhaust port, a blower including an inlet port and an exhaust port, and ducting pneumatically coupling the exhaust port of the filter to the inlet port of the blower, wherein the filter is disposed in the plenum, and adjacent surfaces of the filter and the plenum are substantially equal in surface area. The method includes steps for processing each piece of received material proximate to the work area to thereby generate processed material, isolating the processed material, analyzing the filter for biological hazards, further processing the processed material when biological hazards are not present, and decontaminating the processed material when biological hazards are present. When the filter includes a polishing filter disposed downstream of a roughing filter, the analyzing step is performed on the roughing filter. When the filter includes a HEPA filter, the analyzing step is performed on the upstream surface of the HEPA filter.
In a further aspect, the present invention provides a method for operating a biological hazard mitigation apparatus permitting a mail handling operation in the vicinity of a work area, the apparatus including a plenum pneumatically coupled and proximate to one side of the work area, a filter sized to trap biological hazards and including an exhaust port, a blower including an inlet port and an exhaust port, and ducting pneumatically coupling the exhaust port of the filter to the inlet port of the blower, wherein the filter is disposed in the plenum, including steps for processing each piece of received mail proximate to the work area to thereby generate processed mail and packaging, isolating the processed mail and the packaging from both the apparatus and one another, analyzing at least one of the filter and the packaging for biological hazards, distributing the processed when biological hazards are not present, and decontaminating and then distributing the processed mail when biological hazards are present. When the filter includes a polishing filter disposed downstream of a roughing filter, the analyzing step is performed on the roughing filter. When the filter includes a HEPA filter, the analyzing step can be performed on the upstream surface of the HEPA filter.